1. Field of the Invention
The present invention relates to a novel polyaldimine derivative of a poly(phenylenebisalkylene)poly(phenylamine) which regenerates the poly(phenylenebisalkylene)poly(phenylamine) by hydrolysis, a preparation process of the polyaldimine derivative, a moisture curable polyurethane composition containing the polyaldimine derivative, and the use of the polyurethane composition.
The polyaldimine derivative which regenerates the poly(phenylenebisalkylene)poly(phenylamine) is a useful compound for a curing agent of epoxy resin and polyurethane resin.
The present invention particularly relates to a moisture curable polyurethane composition utilizing the reaction which regenerates the poly(phenylenebisalkylene)poly(phenylamine) by hydrolyzing the polyaldimine derivative and relates to the use of the polyurethane composition.
Further, the present invention relates to a moisture curable polyurethane composition which is industrially useful for the production of anticorrosive paints, floor repairing materials, water proof materials, adhesives, wall covering materials and caulking materials, and also relates to the use of the composition.
2. Description of the Prior Art
Polyurethane resin is excellent in various properties such as rubber elasticity, abrasion resistance and service life, and hence has particularly been used in recent years for anticorrosive paints, floor repairing materials, water proof materials, adhesives, wall covering materials, and caulking materials.
The method for the preparation of polyurethane resin is essentially classified into two groups, that is, one component method and two component method. In the one component method, terminal isocyanato groups of a polyurethane prepolymer cure by atmospheric moisture after application in site. In the two component method, a prepolymer which contains a principal component and a curing agent which contains polyol are mixed at the time of application in site to cause cure.
One component type polyurethane can be used by anybody because of its readiness in application method and has recently attracted much attention.
The one component type polyurethane is referred to as moisture curable polyurethane and the following compositions have conventionally been known in the art.
(1) Moisture curable polyurethane compositions by using a reaction of polyisocyanate with moisture (water), that is, a reaction wherein a part of isocyanate is converted to amine by the decarboxylation of isocyanate water adduct and resultant amine reacts with another polyisocyanate molecule to progress curing.
(2) Moisture curable polyurethane compositions composed of polyaldimine or polyketimine and polyisocyanate (British Patent 1064841 and German Patent 3607996A).
(3) Moisture curable polyurethane compositions composed of polyenamine and polyisocyanate (British Patent 1575666 and German Patent 2125247).
The compositions (1), however, have a relatively good storage stability in a sealed vessel whereas they have a markedly poor curing ability and a disadvantage of foaming. Amine or tin catalysts may be incorporated in order to improve curing ability. The additives, however, lowers storage stability of the compositions, accelerates foaming and cause problems in actual use.
In the compositions (2), polyaldimine or polyketimine reacts with polyisocyanate. Consequently, in order to cure the compositions (2) by atmospheric moisture after application in site, it is required to provide steric hindrance for polyaldimine or polyketimine, or to block isocyanato groups.
British Patent 1064841 and German Patent 3607996A have disclosed polyaldimine and polyketimine having steric hindrance. These compounds, however, exhibit slow curing rate and poor storage stability and are unsuitable for practical application.
Polyaldimine disclosed in German Patent 3607996A, in particular, is prepared from aromatic amine and is excellent in various physical properties such as mechanical strength. However, the compound has a disadvantage that the curing rate is slow and storage stability is poor at increased temperatures.
In the compositions (3), polyenamine also reacts with polyisocyanate. Consequently, when aromatic isocyanate is used as the polyisocyanate isocyanato groups must be blocked similarly to polyketimine and hence the compositions are also unsuitable for practical use.
On the other hand, it has been known that polyenamine can be applied to sealing materials in combination with polyisocyanate having relatively low activity, for example, aliphatic polyisocyanate or alicyclic polyisocyanate. The system has characteristics of non-foaming and rapid cure.
However, polyenamine reacts, though very gradually, with aliphatic or alicyclic polyisocyanate and leads to poor storage stability in a long period or in somewhat increased temperatures, even though preserved in completely sealed containers. As a result, the sealing materials containing such polyenamine have a disadvantage that initial physical properties of the sealing materials cannot be retained or viscosity is remarkably increased and leads to very poor workability. Consequently, any of the conveniently known compositions have been unsatisfactory.
The above mentioned various problems are industrially required to be overcome by providing the sealing materials with below described properties. That is, very important properties of such types of polyurethane are good storage stability in the sealed containers, excellent mechanical strengths in the initial period of application, good retention of initial physical properties during storage at increased temperatures, prevention of gelation, and good stability of viscosity. Rate of curing by atmospheric moisture must also be quick without foaming. The value of the commodity depends upon these properties.
In other words, a moisture curable polyurethane composition is strongly desired which is excellent in storage stability in the sealed containers, i.e., capable of being stored under constant viscosity for a long period, rapidly cured without foaming in the presence of moisture, and outstanding in mechanical strengths after curing.